Looping Video Footage/.MOV file in After Effects

I was given an .mov file that's about 5 minutes long and was asked to create an infinite loop, so that when the video ends, it replays itself from the beginning. I tried looping the footage with Interpret Footage, but it did not work when I rendered the file. I am not sure what I am doing wrong, maybe my render settings are incorrect, so I will greatly appreciate any help! Thank you!

What is the footage like? Is it a camera set up on a tripod or something, not moving, and shooting a static scene? Are there leaves falling/blowing or snow falling ro something? Describe the scene or post a picture or a few frame of the video, and I can help you better.

The rendered file will not loop on its' own. It must be set up in the playback machine or software that plays it to do this. All you can do on the rendering end is make sure that the start and end are able to blend seamlessly - this could be by doing what's called a dissolve loop, or, if you might have a plugin that will cause the graphic you create to loop seamlessly.

At any rate, look to the playback once you deliver the file to be the looping mechanism. DVDs can be programmed to continuously loop, but that's not without pitfalls (sometimes there's a slight glitch when the loop point is reached). What I will often do is create a series of loops as long as the client needs them - say the actual loop is 2 minutes - I would create and render a file which is maybe 20 minutes long. Enough to cover any glitches which might occur at a mechanical loop point (DVD or software playback).

You don't say anything about the playback medium the client plans on using, so it's impossible to be more than general about it.